It is imperative that the exact type of arthritis be identified early and a specific form of treatment be instituted before extensive damage to the articular cartilage occurs. Present diagnostic techniques are frequently unreliabel, and diagnosis by direct visual and histological examination through surgery is painful and expensive. Present reserach at the University of Akron revealed that normal, rheumatoid arthritic and degenerative knees are distinguishable in their respective waveforms, spectral patterns, and other statistical properties. These results brought closer the ultimate goal of developing a non-invasive, accurate, and inexpensive diagnostic tool. It is proposed in this extended study to: 1) adapt the present setup for an extensive clinical use; 2) reduce results "feedback" time by using numerical techniques with a digital computer in the statistical analysis; 3) expose the diagnostic technique to a local group of orthopedic surgeons for a critical evaluation; 4) gain basic understanding of the sound-producing rechanism of the cartilage inside a diseased knee through invivo and invitro modeling; 5) design and develop a prototype cartilage damage detection meter for a mass diagnostic test of incipient cartilage deterioration; and, 6) extend the study to other less prevalent knee joint diseases. It is our opinion that accomplishment of the above objectives would greatly enhance the diagnostic capability of the present system and will determine the feasibility of using the novel technique as a standard clincal diagnostic tool.